Process for preparing complex calcium salt-calcium soap grease



United States Patent 3,068,173 PROCESS FOR PREPARING COMPLEX CALCIUMSALT-CALCIUM SOAP GREASE James R. Roach, Beacon, and Terence B. Jordan,Fishkill,

N.Y., assignors to Texaco inc, New York, N.Y., a corporation of DelawareNo Drawing. Filed Aug. 24, 1959, Ser. No. 335,443 Claims. (Cl. 252-39)This invention relates to complex calcium salt-calcium soap thickenedgreases, and is a continuation-in-part of our copending applicationSerial No. 700,984, filed December 6, 1957, now abandoned.

Calcium salts of low molecular weight fatty acids have been employedheretofore in calcium soap thickened greases, usually in small amountsas stabilizing agents. It has also been found, as disclosed for examplein US. 2,846,392, that calcium base greases of improved load bearing andother properties are obtained by employing as the thickening agent acomplex of a calcium soap with a high proportion of a calcium salt of alow molecular weight fatty acid, formed by heating together a mixture ofcalcium soap and calcium salt in a mol proportion of 1:7 to 1:40,respectively, at a temperature within a high temperature transitionrange above about 400 F., ordinarily occurring in about the range450-550 F., during the grease making process.

We have now found very unexpectedly that improved calcium base greasesare obtained by employing a large proportion of a calcium salt of a lowmolecular weight fatty acid in conjunction with a calcium soap in thegrease preparation and carrying out a heat treating step upon themixture within a low temperature transition range, above 250 F. butbelow the high temperature transition range. The calcium salt isemployed in an amount preferably equal to at least about 13 percent byweight of the finished grease and in a mol ratio of at least about 6:1with the calcium soap. Greases are obtained in this manner having verysuperior extreme pressure properties as compared with calcium soapgreases of the prior art containing calcium salts, including suchgreases containing calcium salts in high proportions obtained by methodsinvolving complexing the calcium soap and calcium salt at hightemperatures. In addition, this method offers very substantialadvantages in convenience and economy over the methods involving a hightemperature heating step. The special object which is attained by ourinvention is the production of greases having the extreme pressure andother properties required to meet US. Steel Specification No. 355 for anextreme pressure steel mill grease in a convenient and reproduciblemanner. The heat treating step within the low temperature range and theamount and proportion of calcium salt employed are critical forobtaining this results by the method of our invention.

The manner in which the calcium soap and calcium salt are associated inthese greases is not exactly known. A large amount of thickening occursduring the heat treating step which is greatly in excess of the separatethickening effects of the calcium soap and calcium salt, indicating thata complex of some type is formed. Also, the greases thus produced arehighly water resistant, which would be very unexpected in a greasecontaining a large amount of uncombined Water soluble calcium salts.However, the typical X-ray diffraction patterns of the calcium salts donot disappear following the low temperature heat ice treating step, incontrast to the results obtained with the high temperature heating stepas reported in the literature, and it therefore appears that a portionof the calcium salt may be uncombined or in the form of some purelyphysical combination with the calcium soap or calcium soap-salt complex.

The preferred procedure in accordance with this invention comprisesemploying in the grease mixture a small amount of an estolide of a highmolecular weight hydroxy fatty acid, as disclosed-in our above-mentionedapplication Serial No. 700,984. Suitable materials of this character areobtained by the interesterification of C to C hydroxy fatty acids andhave average molecular weights in the range from about 500 to about2500. By employing these estolides in amounts from about 0.1 to about2.5 percent by weight based on the weight of the finished grease, alarge improvement in the grease yield is obtained, and the deteriorationin grease yields resulting from the use of the large amounts of calciumsalts in these greases can be thereby overcome to a very substantionextent. The estolide may be added at any stage in the grease makingprocess, either before or after the heating step.

The greases of this invention comprise a lubricating oil as the chiefcomponent thickened to a grease consistency with a calcium lower fattyaicd salt and calcium higher fatty acid soap in a mol ratio betweenabout 6:1 and about 40:1, respectively, most suitably between about 7:1and 25:1, respectively, and preferably from about 7:1 to about 20:1respectively. The calcium salt is very suitably present in an amountbetween about 13 percent and about 24 percent of the weight of thegrease, and preferably in an amount between about 14 percent and about22 percent of the weight of the grease. The calcium soap is verysuitably present in an amount of about 4-10 percent by weight,preferably in an amount of about 4-8 percent by weight of the grease.The calcium salt and calcium soap are preferably employed in proportionssuch as to provide a concentration of the calcium saltcalcium soapcomplex in the range of about 1030 percent by weight in the greasecomposition. The grease may be substantially neutral, or it may containeither a small amount of free acid or free alkali. It is preferablyslightly alkaline with about 0.1-1.5 percent by weight of free alkali,calculated as calcium hydroxide. Greases obtained in accordance with thepreferred procedure wherein a small amount of estolide is employed inthe grease mixture, also contain about 0.1-2.5 percent by weight ofestolide or calcium salt thereof.

The lubricating oils forming the major constituent of these greases maybe any oils of lubricating characteristics which are suitable for use inlubricating greases generally. Such oils include particularly theconventional mineral lubricating oils having Saybolt Universalviscosities in the range from about seconds at F. to about 225 secondsat 210 R, which may be either naphthenic or parafiinic in type or blendsof different oils. The preferred mineral oils are those having SayboltUniversal viscosities in the range from about 300 seconds at 100 F. toabout 100 seconds at 210 F., which may be blends of lighter and heavieroils in the lubricating oil viscosity range.

Synthetic lubricating oils, which may be preferred for obtaining greaseshaving special properties required for certain types of lubricatingservice, include oils prepared by cracking and polymerizing products ofthe Fischer- Tropsch process and the like, as well as other syntheticoleaginous compounds such as diesters, polyesters, polyethers, etc.,having viscosities within the lubricating oil viscosity range. Examplesof suitable diesters include the aliphatic diearboxylic acid diesters,such as di-Z-ethylhexyl sebacate, di(secondary amyl) sebacate,di-Z-ethylhexyl azelate, di-iso-octyladipate, etc. A particularlysuitable class of synthetic polyesters are those described in US.2,628,974, obtained by reacting an aliphatic dicarboxylic acid with aglycol and a monofunctional aliphatic alcohol or acid. Examples ofpolyethers include particularly polyalkylene glycols such aspolyethylene glycol and polypropylene glycol. The sulfur analogs ofthese diesters, polyesters and polyalkylene ethers are also suitable foruse in the grease compositions of this invention. Examples of suitablecompounds of this type include di-Z-ethylhexylthiosebacate,di-n-octylthioadipate, polyethylenethioglycol and the reaction productof adipic acid, thioglycol and 2-ethylhexyl mcrcaptan.

The calcium soap component of the grease is obtained by thesaponification of high molecular weight substantially saturated fattyacids containing -22 carbon atoms. By substantially saturated is meantsuch acids having iodine numbers below about 40, and preferably belowabout 20. The acids may be either unsubstituted or hydroxy substitutedacids, or mixtures thereof. Examples of suitable high molecular weightfatty acid materials which may be employed in the saponification includestearic acid, palmitic acid, myristic acid, lauric acid, 12-hydroxystearic acid, 9-hydroxystearic acid, 9,10-dihydroxystearic acid,S-hydroxypalmitic acid and the monoesters and glycerides of such acids.The preferred saponifiable materials contain a major proportion ofunsubstituted fatty acid materials. Very advantageously, a mixture ofacids of the character described containing a major proportion ofunsubstituted fatty acids having from 12 to 16 carbon atoms permolecule, or the esters of such acids, is employed.

The calcium salt component of these greases is derived from lowmolecular weight saturated fatty acids containing 1-3 carbon atoms. Thecalcium salt can thus be calcium formate, calcium acetate, calciumpropionate, or mixtures thereof. In further description of theinvention, calcium acetate will be used to illustrate the calcium saltcomponent of these greases, although it will be understood that calciumsalts of formic and propionic acids may be substituted therefor.

In accordance with the method of this invention, a grease mixturecomprising a calcium salt and calcium soap in the above indicatedproportions together with lubricating oil constituting all or a portionof the lubricating oil contained in the finished grease is heated at anelevated temperature of at least about 250 F., preferably at least 255F., but below about 400 F. until at least substantial thickening hasoccurred. The length of time required varies with the temperature, andmay range from a few minutes at the higher temperatures to several hoursat lower temperatures within the disclosed range. It is ordinarily from0.25 to 4 hours. The heating is preferably carried out at a temperatureof at least about 275 F., in order to obviate excessively long heatingtimes, and not in excess of about 375 F., in order to avoid localoverheating of the grease mixture to temperatures within the hightemperature transition range. It is preferably carried out at atemperature below about 350 F., very suitably at a temperature in therange 260-325 F., and particularly in the range 260310 F., in order toobtain improved storage characteristics as disclosed in the above citedapplication Serial No. 700,984. Most advantageously, the heating step iscarried out at a temperature in the range from about 290 F. to about 350F. for a period from about 30 minutes to about 2 hours.

The grease mixture may be obtained by coneutralizing the high molecularweight fatty acid material and low molecular weight fatty acid materialin situ by means of a suitable basically reacting calcium compound suchas calcium oxide or calcium hydroxide, or by forming the calcium salt inthe presence of the calcium soap. It may also be formed by employing apreformed acid salt of low molecular weight fatty acid, represented bythe formula Ca(C H O- .(C H O for the acetate salt, wherein n is aninteger having a value of 1-3. The preferred procedure comprises in situsaponification and neutralization under substantially anhydrousconditions, wherein the low molecular weight fatty acid material isadded to the saponification mass after at least substantialsaponification has occurred. This overcomes the problem of graininess ofthe product due to the formation of coarse crystals of calcium saltwhich tend to form when the low molecular weight acids are added to themixture containing high proportions of unreacted calcium hydroxide.

In carrying out the grease preparation by the preferred procedure, thegrease kettle is charged with the higher fatty acid material, the totalamount of calcium hydroxide required and lubricating oil which is asubstantially nonreactive under the saponification conditions, and themixture stirred or otherwise agitated so as to form an intimate mixture.The kettle is then heated and lower molecular weight fatty acid materialadded gradually after at least substantial saponification has occurredand when the temperature of the mass is below the boiling point of theacid material, preferably below about 200 F. The grease mixture isheated at below about 200 F. for a sufficient time to complete thesaponification and neutralization reactions and then at a highertemperature to dehydrate and form the salt-soap complex as describedabove. The grease mixture may be cooled in any convenient manner and ispreferably finished by milling. Additional lubricating oil may be addedat any stage of the process.

The following examples are given for the purpose of further disclosingthe invention.

EXAMPLE I A series of greases comprising calcium acetate and calciumsoap in a 7:1 mol ratio was prepared in accordance with this inventionby the method involving forming the calcium salt of the low molecularweight acid in situ in the saponification mass and heating the greasemixture at a maximum temperature between about 275 F. and 375 F. Thelubricating oil employed was a blend in a 2.3 ratio by weightrespectively of a refined paraflinic distillate oil having a SayboltUniversal viscosity of about 185 at F. and a refined residuum from amixed base crude having a Saybolt Universal viscosity of about 156 at210 F. The calcium soap was obtained by saponification of commercialcoconut oil fatty acids, having a saponification number of 253 and aniodine number of 12.2.

The following is a detailed description of the preparation of one ofthese greases: A grease kettle was charged with 25.7 pounds of minerallubricating oil, 2.32 pounds of coconut oil fatty acids, and 3.68 poundsof lime, and the mixture heated With stirring and with circulation ofthe grease mixture through an outside recycle line containing a gearpump in order to obtain thorough mixing. When the temperature of themixture had reached F 4.65 pounds of glacial acetic acid were added andthe heating continued at 3l03l8 F. The temperature was maintained at310-318 F. for 2 hours and the mixture then cooled to 250 F. at a rateof about 2 F. per minute, while adding an additional 30.8 pounds ofmineral lubricating oil. Phenylalphanaphthylamine (0.175 pound) was thenadded and the grease finished by milling in a Manton-Gaulin homogenizerat 7000 p.s.i.g.

The greases obtained as described above were of good texture andappearance, having excellent lubricating properties including highextreme pressure properties represented by CK. loads in the Timken Testabove 50, and generally above 60. Greases of this same composition whichwere prepared in substantially the same manner but with heating attemperatures above 400 F. had very markedly lower load bearingproperties, and greases meeting the requirement of U.S. SteelSpecification No. 355 for a minimum O.K. load of 40 in the Timken Testcould not consistently be produced. Also, greases meeting therequirement of this specification for a 5 percent maximum loss in theWater Washout Test were not obtained when the grease mixture was heatedat above 400 F.

The following table shows the extreme pressure and other properties ofrepresentative greases of the above series, and also comparatively for arepresentative grease prepared by the high temperature method. All ofthe grease preparations were carried out in substantially the samemanner except for the dilference in the maximum temperature during theheat treating step, with milling or shearing so as to produce themaximum yield. Grease No. 2 of the table is that obtained in thepreparation which is described in detail above. In the preparation ofgrease No. 3, the charge to the grease kettle also con tained 0.3 poundof an estolide of IZ-hydroxystearic acid having an average molecularweight of about 1600.

Table I Grease No 1 2 3 Composition, percent:

Ca acetate 15.0 17.2 15.0 Ca soap 6. 7. 2 6. 0 Excess Ca(OH)z 0. 5 1.01.0 Calcium soap at estol e of 12-hydroxystearic acid 0 0 0.5Phenylalphanaphthylamina 0. 5 0. 5 0. 5 Mineral Oil Re- Re- Remaindermainder maiuder Ca acetate-Ca soap mol ratio- 7. 5:1 7. 3:1 7. 5 1Preparation: T Maximum temperature, F. 500 318 357 ests:

ASTM Penetration at 77 Unworked 230 281 294 Worked, 00 strokes 298 388346 Worked, 10,000 stro es 353 382 326 Dropping Point. F 500+ 500+ 500+Timken Test, O.K. load, lbs. 45 75 7 Water Washout Test, D-1264,

Grease loss, percent 23. 5 3. 5 2. 5

While higher yields were obtained by the high tempera- 0 ture method, asshown by the data, this was overcome to a considerable extent in thegreases of our invention by employing a small amount of estolide in thegrease mixture, as shown by grease No. 3.

EXAMPLE II As an example of a grease of this invention containing adifferent calcium soap, a grease was prepared by the low temperaturemethod wherein the calcium soap Was calcium 12-hydroxystearate. Thelubricating oil employed in the grease was that described in Example I.

The grease preparation was carried out substantially as described inExample I, with formation of the calcium salt in situ in thesaponification mass and with a heat treatment for two hours at 310320 F.following the dehydration.

The following table shows the properties of the above grease incomparison with those of a grease (grease No. 2) obtained in the samemanner except that the grease mixture was heated to 500 F. The tablealso shows the properties of a grease prepared by the low heat procedurein the same manner except that an unsaturated fatty acid was employed asthe saponifiable material (grease No. 3). The unsaturated fatty acidemployed was oleic acid, having an iodine number of 86.

Table II Grease No 1 2 3 Composition:

Ca acetate 17. 5 15.0 17. 5 Ca soap 7. 2 6.0 7. 2 Excess Ca (OH); 0.8 1.0 0. 8 Calcium soap 0! estolide of IZ-hydroxystearic acid 0.5 0.5 0. 5Phenylalphanaphthylamine- 0.5 0. 55 0. 5 Mineral Oil Remainder RemainderRemainder Ca acetate-Ca soap mol ratio- 10:1 10:1 9:1 Preparation:

Maximum Temperature, F. 320 500 320 Tests:

ASIM Penetration at 77 F.

Unworked 202 368 246 Workerl, 60 strokes 279 373 341 Worked, 10,000strokes. 299 294 352 Dropping Point, F 500+ 500+ 500+ Timkeu Test, 0.11.load, lbs" 40 33 As shown by the above data, the advantage 1n extremepressure properties is also obtained by the method of this inventionemploying hydroxy fatty acids as the saponifiable materials, differentlyfrom the unsaturated fatty acids with which no such advantage isobtained. In addition to the excellent extreme pressure properties shownin the table, grease No. 1 met the other requirements of U5. SteelSpecification No. 355, including the requirements for low water loss,good oxidation resistance and high shear stability.

In comparison with greases prepared by the method of this invention fromunsubstituted fatty acids, greases prepared from hydroxy fatty acids areobtained in higher yields, but they absorb more water and undergo alarger amount of penetration change after water absorption, and they aretherefore considered less desirable for use in the presence of water.

Obviously many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof and only such limitations should be imposed as areindicated in the appended claims.

We claim:

1. The method of preparing an extreme pressure calcium base greasethickened with about 17-30 percent by weight of a calcium salt-calciumsoap complex which comprises forming a mixture comprising a lowmolecular weight fatty acid material selected from the class consistingof saturated C fatty acids, their esters and calcium acid salts, and ahigh molecular weight fatty acid material selected from the classconsisting of substantially saturated unsubstituted andhydroxy-substituted C fatty acids and C fatty acid mixtures, theiresters and calcium salts, in at least a portion of the lubricating oilcontained in the finished grease, adding to said mixture a basicallyreacting calcium compound in an amount sufiicient for converting all ofthe said fatty acid materials into their normal calcium salts, heatingthe reaction mixture for a sufficient time to complete allsaponification and neutralization reactions, further heating it at anelevated temperature until at least substantial thickening has occurred,and thereafter cooling the said mixture and adding any additionallubricating oil required to obtain a grease of the desired grade, saidlow molecular weight fatty acid material being employed in the saidreaction mixture in an amount sufficient to give a ratio of calcium lowmolecular weight fatty acid salt to calcium high molecular weight fattyacid soap of 7:1 to 25:1.

2. The method according to claim 1 wherein the said low molecular weightfatty acid salt is calcium acetate.

3. The method according to claim 1 wherein the said mixture is heated ata maximum temperature below about 375 F.

4. The method according to claim 1 wherein the said mixture is heated ata maximum temperature in about the range 260350 F.

5. The method according to claim 1 wherein an estolide of a hydroxyfatty acid containing -22 carbon atoms is added to the grease mixturebefore completion of the said saponification and neutralizationreactions.

6. The method according to claim 1 wherein the said lubricating oil is amineral lubricating oil.

7. The method of preparing an extreme pressure calcium base greasethickened with about 17-30 percent by weight of a calcium salt-calciumsoap complex which comprises saponifying a high molecular weight fattyacid material selected from the class consisting of substantiallysaturated unsubstituted fatty acids and hydroxy substituted C fattyacids, C1248 fatty acid mixtures and esters thereof with a basicallyreacting calcium compound in the presence of at least a portion of thelubricating oil contained in the finished grease, adding a saturated Cfatty acid and any additional basically reacting calcium compoundrequired for the neutralization of the said C fatty acid to thesaponification mixture after at least partial saponification of the saidhigh molecular weight fatty acid material has occurred, dehydrating thegrease mixture obtained, heating it at a temperature in about the range260-350" F. until at least substantial thickening has occurred, andthereafter cooling the grease mixture and adding any additionallubricating oil required to give a grease of the desired grade, said Cfatty acid being added to the saponification mixture in an amountsufficient to give a ratio of calcium low molecular weight fatty acidsalt to calcium high molecular weight fatty acid soap of 7:1 to 25:1 inthe grease.

8. The method according to claim 7 wherein an estolide of a hydroxyfatty acid containing 1022 carbon atoms is added to the grease mixturebefore completion of the said saponification and neutralizationreactions.

9. A calcium base grease having superior extreme pressure propertiesrepresented by an OK. load in the Timken Test above 50, consistingessentially of a lubricating oil as the chief component thickened to agrease consistency with a complex mixture of 13-24 percent by weight,based on the weight of the grease, of calcium acetate and 4-10 percentby weight, based on the weight of the grease, of a calcium soap selectedfrom the group consisting of calcium soaps of unsubstituted fatty acidsand hydroxy substituted fatty acids containing 12-18 carbon atoms, andmixtures thereof, said calcium salt and said calcium soap being in a molratio between about 7:1 and 20:1 respectively, said grease being heatedduring the preparation thereof at an elevated temperature of at least255 F. but below 400 F.

10. A lubricating grease according to claim 9 containing about 0.1-2.5percent by weight of a material selected from the class consisting ofcalcium soaps of estolides of hydroxy fatty acids containing 10-22carbon atoms.

11. A lubricating grease according to claim 9 which has been heatedduring the preparation thereof at a maximum temperature below about 350F.

12. A lubricating grease according to claim 9 containing 14-22 percentby weight of said calcium salt and 4-8 percent by weight of said calciumsoap.

13. A lubricating grease according to claim 9 wherein the saidlubricating oil is a mineral oil.

14. A lubricating grease according to claim 9 wherein the said calciumsalt and said calcium soap are present in a mol ratio between about 7:1and about 20:1.

15. A process for preparing complex calcium salt-calcium soap thickenedgreases wherein the mol ratio of calcium salt to calcium soap is between7:1 and :1 which comprises saponifying a mixture of coconut fatty acid,an estolide of the hydroxy fatty acid containing 10-24 carbon atoms anda compound selected from the group consisting of an aliphaticmonocarboxylic acid containing l-3 carbon atoms and an acid salt thereofin a lubricating oil with a basic reacting calcium compound, subjectingthe saponified reaction mixture to heat treatment at a temperaturebetween 255 and 325 F. to effect dehydration of the reaction mixture andformation of the calcium salt-calcium soap complex and cooling saiddehydrated reaction mixture to form a complex calcium saltcalcium soapthickened grease characterized by low wear, storage stability, shearstability and water resistance.

References Cited in the file of this patent UNITED STATES PATENTS2,862,884 Dilworth et al Dec. 2, 1958 2,877,181 Dilworth et al. Mar. 10,1959 2,898,297 Schott et al. Aug. 4, 1959 2,973,321 Morway et al. Feb.28, 1961 FOREIGN PATENTS 785,509 Great Britain Oct. 30, 1957 789,855Great Britain Jan. 29, 1958 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 3,068, 173 December 11 1962 James R. Roach et al.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column l line 55, for "results" read result column 2 lines 20 and 21,for "substantion" read substantial line 26, for "aicd" read acid column5, Table I, under the heading "Grease N09", line 5, for "at" read ofcolumn 6, Table 11, under the heading "2" third line from the bottom for"294" read 394 column' 6, line 59, after "temperature" insert of atleast 255 F, but below 400 F. B

Signed and sealed this 11th day of June 1963 (SEAL) Attest:

ERNEST w. SWIDER DAVID D Attesting Officer Commissioner of PatentsUNITED STATESPATENT OFFICE CERTIFICATE OF CORRECTION Patent No,3,068,173 December ll, 1962 James R. Roach et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 1, line 55, for "results" read result column 2, lines 20 and 21,for "substantion" read substantial line 26, for "aicd" read acid column5, Table I, under the heading Grease N06", line 5, for "at" read ofcolumn 6, Table II, under the heading "2", third line from the bottom,for "294" read 394 column' 6, line 59, after "temperature" insert of atleast 255 IE, but below 400 F.

Signed and sealed this llth day of June 1963,,

(SEAL) Attest ERNEST w. SWIDER DAVID D Attesting Officer Commissioner ofPatents

1. THE METHOD OF PREPARING AN EXTREME PRESSURE CALCIUM BASE GREASETHICKENED WITH ABOUT 17-30 PERCENT BY WEIGHT OF A CALCIUM SALT-CALCIUMSOAP COMPLEX WHICH COMPRISES FORMING A MIXTURE COMPRISING A LOWMOLECULAR WEIGHT FATTY ACID MATERIAL SELECTED FROM THE CLASS CONSISTINGOF SATURATED C1-3 FATTY ACIDS, THEIR ESTERS AND CALCIUM ACID SALTS, ANDA HIGH MOLECULAR WEIGHT FATTY ACID MATERIAL SELECTED FROM THE CLASSCONSISTING OF SUBSTANTIALLY SATURATED UNSUBSTITUTED ANDHYDROXY-SUBSTITUTED C18 FATTY ACIDS AND C12-18 FATTY ACID MIXTURES,THEIR ESTERS AND CALCIUM SALTS, IN AT LEAST A PORTION OF THE LUBRICATINGOIL CONTAINED IN THE FINISHED GREASE, ADDING TO SAID MIXTURE A BASICALLYREACTING CALCIUM COMPOUND IN AN AMOUNT SUFFICIENT FOR CONVERTING ALL OFTHE SAID FATTY ACID MATERIALS INTO THEIR NORMAL CALCIUM SALTS, HEATINGTHE REACTION MIXTURE FOR A SUFFICIENT TIME TO COMPLETE ALL SAPONFICATIONAND NEUTRALIZATION REACTIONS, FURTHER HEATING IT AT AN ELEVATEDTEMPERATURE UNTIL AT LEAST SUBSTANTIAL THICKENING HAS OCCURED, ANDTHEREAFTER COOLING THE SAID MIXTURE AND ADDING ANY ADDITION ALLUBRICATING OIL REQUIRED TO OBTAIN A GREASE OF THE DESIRED GRADE, SAIDLOW MOELCULAR WEIGHT FATTY ACID MATERIAL BEING EMPLOYED IN THE SAIDREACTION MIXTURE IN AN AMOUNT SUFFICIENT TO GIVE A RATIO OF CALCIUM LOWMOLEUCLAR WEIGHT FATTY ACID SALT TO CALCIUM HIGH MOLECULAR WEIGHT FATTYACID SOAP OF 7:1 TO 25:1.